#!/usr/bin/env python3

import json
import os
import subprocess
import sys

import tanken

"""Dict of dicts associating a second person to an amount"""
balance = {}

name2num = {}
num2name = {}

"""Dict associating users with their last change"""
last_change = {}

group_id = os.environ["GSB_GROUP_ID"]

send_cmd = os.environ["GSB_SEND_CMD"]

"""Run without changing the stored state"""
dry_run = False

def record(sender, recipient, donor, amount):
    """Apply change to the balance and save it"""

    # Only change anything if this is not a dry run
    if not dry_run:
        balance[donor][recipient] += amount
        balance[recipient][donor] -= amount

        if not sender in last_change:
            last_change[sender] = []

        last_change[sender].append([recipient, donor, amount])

def to_cent(euro):
    euro = euro.split('.')
    if len(euro) > 2:
        raise TypeError
    euro[0] = int(euro[0])
    if len(euro) < 2:
        euro.append(0)
    else:
        if len(euro[1]) == 1:
            euro[1] = int(euro[1]) * 10
        else:
            euro[1] = int(euro[1])
    return euro[0] * 100 + euro[1]

def to_euro(cents):
    return str(cents/100)

def send(msg):
    subprocess.run(send_cmd.split(' '), input=msg.encode())

def create_summary(user):
    summary = ""
    total = 0
    p_balances = balance[user] # failes if user is not in balance
    for person in p_balances:
        amount = p_balances[person]
        if amount == 0:
            continue
        total -= amount
        summary += "\t{} {} {}\n".format("<-" if amount < 0 else "->", person, to_euro(abs(amount)))
    if summary == "":
        summary = "\tAll fine :)\n"
    else:
        summary += "\tBalance: {}".format(to_euro(total))
    summary = user + ":\n" + summary
    return summary

def create_total_summary():
    summary = "Summary:"

    for person in balance:
        summary += '\n'
        summary += "* " + create_summary(person)

    return summary

def create_members():
    r = ""
    for m in name2num:
        r += m + ": " + name2num[m] + "\n"
    return r

def create_help():
    return """
Usage: send a message starting with '!' followed by a command
Commands:
ls | list - print all registered members
help - print this help message
reg name - register the sender with the name: name
sum [name] - print a summary

split amount person [persons] - split amount between the sender and persons
teil amount person [persons] - split amount between the sender and persons

schieb amount recipient - give money to recipient
gib amount recipient - give money to recipient
zieh amount donor - get money from donor
nimm amount donor - get money from donor

tanken amount person [info] - calculate fuel costs and add them to the balance

fuck - rewind last change

Happy Geldschieben!
"""

def handle_input(inp):
    for l in inp.splitlines():
        message = json.loads(l)["envelope"]

        sender_number = message["source"]
        if not "dataMessage" in message:
            continue
        else:
            message = message["dataMessage"]
            if message["groupInfo"] and message["groupInfo"]["groupId"] != group_id:
                continue
            body = message["message"].lower().splitlines()

        w = body[0].split(' ')

        cmd = w[0]

        global last_change

        # supported commands are:
        # "!reg"           register a name for this number
        # "!sum"           send a summary to the group
        # "!list" "!ls"    list members
        # "!help"          print all commands
        # "!split" "!teil" split amount between group
        # "!schieb" "!gib" give money to somebody
        # "!zieh" "!nimm"  add debt of somebody
        # "!tanken"        calculate fuel cost parts
        # "!fuck"          rewind last change
        if cmd == "!reg":
            if len(w) != 2:
                send('ERROR: not in form "!reg name"')
                continue

            if w[1] in name2num:
                send("ERROR: name already registered")
            elif sender_number in num2name:
                send("ERROR: you are already registered")
            else:
                num2name[sender_number] = w[1]
                name2num[w[1]] = sender_number

                # add to balance
                nm = {}
                for m in balance:
                    balance[m][w[1]] = 0
                    nm[m] = 0
                balance[w[1]] = nm

        elif cmd == "!sum":
            if len(w) == 1:
                send(create_total_summary())
            elif len(w) == 2:
                if w[1] in name2num:
                    send("Summary:\n" + create_summary(w[1]))
                else:
                    send("ERROR: name not registered")
            else:
                send('ERROR: not in form "!sum [name]"')

        elif cmd == "!list" or cmd == "!ls":
            send(create_members())

        elif cmd == "!help":
            send(create_help())

        elif cmd == "!split" or cmd == "!teil":

            if not sender_number in num2name:
                send('ERROR: you must register first')
                continue

            if len(w) < 3:
                send('ERROR: not in form "!{} [amount] [name]+"'.format(cmd))
                continue

            try:
                amount = to_cent(w[1])
            except:
                send("ERROR: amount musst be a number")
                continue

            # -2 because amount and cmd; +1 because the sender is part of the group
            persons = len(w) - 2 + 1
            amount_per_person = int(amount/persons)

            if sender_number in num2name:
                recipient = num2name[sender_number]
            else:
                send("ERROR: you must register first")
                continue

            msg = "Split {} between {} -> {} each\n".format(to_euro(amount),
                                                            persons,
                                                            to_euro(amount_per_person))
            # clear change history
            last_change[sender_number] = []
            for p in w[2:]:
                if not p in name2num:
                    msg += p + " not known. Please take care manually\n"
                else:
                    record(sender_number, recipient, p, amount_per_person)

            msg += "New Balance:\n"
            msg += create_summary(recipient)
            send(msg)

        elif cmd in ["!schieb", "!gib", "!zieh", "!nimm"]:
            if len(w) != 3:
                send('ERROR: not in form "!{} amount recipient"'.format(cmd))
                continue

            if not sender_number in num2name:
                send('ERROR: you must register first')
                continue

            if w[1] in name2num:
                recipient = w[1]
                amount = w[2]
            elif w[2] in name2num:
                recipient = w[2]
                amount = w[1]
            else:
                send('ERROR: recipient not known')
                continue

            sender = num2name[sender_number]

            try:
                amount = to_cent(amount)
            except:
                send("ERROR: amount musst be a number")
                continue

            if amount < 0:
                send("ERROR: amount must be positiv")
                continue

            if cmd in ["!zieh", "!nimm"]:
                amount *= -1

            # clear change history
            last_change[sender_number] = []

            record(sender_number, sender, recipient, amount)

            p_balance = balance[sender][recipient]

            send("New Balance: {} {} {} {}\n".format(sender,
                                                        ("->" if p_balance > 0 else "<-"),
                                                        to_euro(abs(p_balance)),
                                                        recipient))
                
        elif cmd == "!tanken":
            if len(w) < 3:
                send('ERROR: !tanken not in form "!tanken amount person [info]"')
                continue
            try:
                amount = to_cent(w[1])
            except:
                send("ERROR: amount musst be a number")
                continue

            if w[2] in name2num:
                recipient = w[2]
            elif sender_number in name2num:
                recipient = num2name[sender_number]
            else:
                send("ERROR: recipient unknown")
                continue

            parts, err = tanken.tanken(body[1:], amount)

            if err != None:
                send("ERROR: " + err)
                continue

            # clear change history
            last_change[sender_number] = []

            msg = ""
            for p in parts.items():
                msg += p[0] + ": {}km = {}\n".format(p[1][0], to_euro(p[1][1]))
                if p[0] != recipient:
                    if p[0] in name2num:
                        record(sender_number, recipient, p[0], p[1][1])
                    else:
                        msg += p[0] + " not known. Please take care manually\n"

            msg += "New Balance:\n"
            msg += create_summary(recipient)
            send(msg)

        elif cmd == "!fuck":
            if not sender_number in num2name:
                send("ERROR: you must register first")
                continue

            if not sender_number in last_change:
                send("Nothing to rewind")
                continue

            # copy list
            changes = [x for x in last_change[sender_number]]

            # clear change history
            last_change[sender_number] = []

            msg = num2name[sender_number] + ": sorry I fucked up!\n Rewinding:\n"
            for change in changes:
                msg += "{} -> {} {}\n".format(change[0], change[1], to_euro(change[2]))
                record(sender_number, change[1], change[0], change[2])

            send(msg)


def main():

    if len(sys.argv) > 1 and sys.argv[1] in ["-d", "--dry-run"]:
        global dry_run
        dry_run = True
        print("Dry Run no changes will apply!")

    store_path = os.environ["GSB_STORE_PATH"]
    balance_path = store_path + "/balance.json"
    registration_path = store_path + "/registration.json"
    last_change_path = store_path + "/last_change.json"

    global balance
    if os.path.isfile(balance_path):
            balance = json.load(open(balance_path, "r"))

    global name2num
    global num2name
    if os.path.isfile(registration_path):
            name2num = json.load(open(registration_path, "r"))
            for name in name2num:
                num2name[name2num[name]] = name

    global last_change
    if os.path.isfile(last_change_path):
        last_change = json.load(open(last_change_path, "r"))

    handle_input(sys.stdin.read())

    with open(balance_path, "w") as f:
        json.dump(balance, f)

    with open(registration_path, "w") as f:
        json.dump(name2num, f)

    with open(last_change_path, "w") as f:
        json.dump(last_change, f)

if __name__ == "__main__":
    main()